Massive flood scarred the surface of Mars less than 500 million years ago

Water carved channels at least 70 meters deep and 40 kilometers wide.

Mars clearly had a watery history, with strong evidence of flowing streams and even some indications that an ocean was present in the distant past. The fate of Mars' water isn't understood, but there's evidence that some of it may have gone underground and is currently circulating in the bedrock of the red planet.

A study being released by Science finds further evidence that some of Mars' underground waters have burst to the surface violently. Using radar imaging, a team of scientists has tracked a series of channels buried under more recent features and has followed them back toward the source. The imaging showed that the main channel was about 40 kilometers wide and at least 70 meters deep. That's roughly the same size as the features carved by the largest well-characterized floods on Earth.

The work involved a radar instrument called SHARAD on the Mars Reconnaissance Orbiter. The radar can penetrate some surface features, revealing several layers beneath—depending on how they reflect the incoming radiation. This turned out to be extremely useful at the feature in question, Marte Vallis. It's one of a number of features on the Martian surface that suggests catastrophic flooding, but it's quite young at 500 million years old, long after water was thought to be common on the Martian surface. Unfortunately, studying it is complicated by the fact that it has been buried by an even younger feature: volcanic eruptions that make it difficult to even identify the source of the flood waters.

With the radar, however, a number of features that are invisible on the surface became apparent. Images revealed a number of smaller branching channels surrounding some small islands, all cut into the bedrock and since buried under the lava. These were roughly 40 meters deep, and the authors suggest they were carved during the early stage of the flooding.

That early stage later resolved into a single huge channel that was cut even deeper. This feature is about 40 kilometers wide (combined, the whole system is roughly 100km in width). Here the authors estimate the waters carved out the rock to a depth of at least 70m, and possibly over 115m—it's hard to tell, because it cut entirely through the bedrock and into a layer below that doesn't reflect radar well. At a minimum, that's twice the depth that had been previously estimated for Marte Vallis.

The authors note that the only confirmed flood feature of similar magnitude on Earth is also the largest we know of: the draining of Lake Missoula, which broke through a glacial dam and wiped out a lot of the soil of the eastern side of Washington during the last glacial period.

On its own, this was an impressive result, but the radar data also extended the known extent of the channels another 100km (up from 1,000km). That was enough to suggest the site that was the origin of the massive outburst of water, a feature called Cerberus Fossae. Whatever triggers these events, they tend to empty the source area of so much water that the surface terrain collapses, creating what's termed "chaos terrain." Apparently, Cerebrus Fossae fits the bill; it's a series of parallel faults that were thought to have been caused by volcanic activity.

Given the magnitude of the water involved, the obvious question is what's going on underneath Mars to collect it all in one place. Given that Cerebrus Fossae has been volcanically active, that's one reasonable guess as to what expelled the water.

Wouldn't it be appropriate to refer to the correct physical state of water at Mars temperatures -- ice?

How does ice circulate under the surface? Sublimation?

Well if there is volcanic activity, I'm assuming the lava/magma is hot enough to melt the ice, make water, and steam. I'm not saying it will stay that way, just that it can get there. Further, if the water is deep enough, the temperature could be warmer, if do to nothing else then friction in the rock.

I thought the water evaporated was the common theory? When mars lost it's magnetic field solar winds took away the atmosphere and with no air pressure the water evaporates which then gets taken away from solar winds.

Do they think the water has evaporated from the surface, or that it has all gone underground? I thought water was realtively common in the universe so we should expect to find it on any rocky planet.

Much of it is probably under the visible surface. The low surface temperature means that any water on the surface can't remain liquid, but the very low atmospheric pressure means that any ice readily sublimates. So large water formations will freeze and then sublimate until they're covered by a protective layer of dust which halts the sublimation. The water vapor from sublimation will then redeposit elsewhere as frost, such as permanent ice caps at the poles (where a vast amount of water is locked up) and seasonally in certain areas (frost deposition was recorded by one of the Viking landers).

Wouldn't it be appropriate to refer to the correct physical state of water at Mars temperatures -- ice?

How does ice circulate under the surface? Sublimation?

Well if there is volcanic activity, I'm assuming the lava/magma is hot enough to melt the ice, make water, and steam. I'm not saying it will stay that way, just that it can get there. Further, if the water is deep enough, the temperature could be warmer, if do to nothing else then friction in the rock.

Wouldn't it be appropriate to refer to the correct physical state of water at Mars temperatures -- ice?

How does ice circulate under the surface? Sublimation?

Well if there is volcanic activity, I'm assuming the lava/magma is hot enough to melt the ice, make water, and steam. I'm not saying it will stay that way, just that it can get there. Further, if the water is deep enough, the temperature could be warmer, if do to nothing else then friction in the rock.

Are there any indications of recent volcanic activity?

I thought that it said most of the features had been covered up by lava, which indicates that there was volcanic activity after the flood event (which could mean that there was volcanic activity before the event).

And yea, verily did Noah shoot the rapids, along with his sons Sem, Ham, and Japeth, and their wives, and his wife, and the animals, both male and female, and he did peel out, yet did not roll, for his ark was not capable thereof.

There have been 9 500-million year periods since the formation of the planet. So we have a 11% chance that anything we see will be from one of those years, picking any year at random. But surface features are newer at the top. So there's like 99% chance that it was in the last 500m years.

This isn't exciting news. This isn't news at all.

Where in the world do you get your 99% figure from? It certainly doesn't apply to Mars, where outflows like this that date from over 3.5 billion years ago are clearly visible. The reason? Mars doesn't have plate tectonics rearranging its surface.

There have been 9 500-million year periods since the formation of the planet. So we have a 11% chance that anything we see will be from one of those years, picking any year at random. But surface features are newer at the top. So there's like 99% chance that it was in the last 500m years.

This isn't exciting news. This isn't news at all.

Where in the world do you get your 99% figure from? It certainly doesn't apply to Mars, where outflows like this that date from over 3.5 billion years ago are clearly visible. The reason? Mars doesn't have plate tectonics rearranging its surface.

I think if anything the majority of flows happened earlier in the planets history rather than later, back when Mars was much warmer and had a more substantial atmosphere. Mars of today is like a person on life support. Barely hanging on but obviously at the end (or past the end) of any meaningful activity.

damnit, prokaryotes. if you hadn't dawdled so much, we might've evolved in time to witness this.

Then again things might have turned out much different had that happened. Sorta sucks because we're too late to see Mars in a bit better light but we're here because of what preceded so we're stuck. We've barely scratched the surface though and who knows what might be waiting for us in caves around the planet. I think if we find any life it'll probably be there.

There have been 9 500-million year periods since the formation of the planet. So we have a 11% chance that anything we see will be from one of those years, picking any year at random. But surface features are newer at the top. So there's like 99% chance that it was in the last 500m years.

This isn't exciting news. This isn't news at all.

Yeah, it's more like anti-news which just sucks all the joy of living out through your ears and leaves it in a shallow puddle at your feet.

This is nice. I'm surprised NASA got this far on showing pics versus their other findings that are hidden from public. I sometimes have to head to ESA to get more pictures and in full detail. Where's the metal-like artifact, NASA? The pyramids? The so-obvious artificially made structures? Nothing will convince me further than knowing that Mars was a habitable place, visited and used as a stopping land for something in past civilizations. But of course, the elites have them covered up and I'm just another troll, conspiracy theorist, <insert excuse in denial> on the internet. Great pics though, we need humans up there and back.

Interesting, though I had to do some digging to understand the context.

The Cerberus Fossae are responsible for more obvious flood channels, such as the Athabasca Valles. Those are also lava covered, with the simplest suggestion that "the water flood and lava flows are essentially contemporaneous". [ http://en.wikipedia.org/wiki/Athabasca_Valles ]

The volcanic center responsible for the magma center that ripped the Cerberus Fossae apart is the Elysium volcanic province, situated on Elysium Planitia. Interestingly, it isn't even the youngest or largest province. "Elysium Mons is only about one-fifth the volume of Arsia Mons." [ http://en.wikipedia.org/wiki/Volcanolog ... c_province ]

Even more interestingly, this is the region that InSight will visit 2016 to measure its, and more importantly, Mars' seismological activity. "These faults, known as the Cerberus Fossae (see figure 2) are around 1000km from the proposed landing site. This figure is taken from a paper by Roberts et al. which shows evidence that these faults are likely still active today." [ http://areology.org/2013/01/07/seismicity-of-mars/ ]

Other (or the same) evidences that I have seen mentioned are rocks that are too large to have moved without seismic activity, and that looks to have been moved within the last 100 000 years. (I should google that, but I'm short on time.)

I thought the water evaporated was the common theory? When mars lost it's magnetic field solar winds took away the atmosphere and with no air pressure the water evaporates which then gets taken away from solar winds.

Some water will have evaporated, as evidenced by D/H (deuterium to hydrogen) ratios in water vapor compared to Earth norm. Curiosity got D/H ~ 5 times Earth, for instance, implying lighter hydrogen has been preferentially lost to space.

However, some water is believed to have been deposited as massive crustal water ice contents. Try hundreds of meters of ice, hopefully covering some habitable liquid water table beneath, or at least providing ice-liquid water surfaces to live of.

Curiosity's results would have to be tested against models of water loss and water ice deposition, seeing how ice likely would preferentially bind the heavier D first. I.e. Mars may have lost more than 4/5 of its water to space, if there remains massive ice deposits such as the polar regions hints at.

And as always, atmospheric loss processes are not so simple and different on different planets (mass, distance to Sun, magnetosphere, atmosphere pressure profile and composition, geology, eventual biology). Earth lost most of its initial atmosphere to its crust by subsequent sequestration of carbon, while Venus preferentially has lost its hydrogen and not much else despite having no magnetic field to speak of.

Mars likely lost its atmosphere to space because it isn't much massive but solar wind attrition is ~ 1/4th of Earth's, while I have read the current multipolar field remains _help_ atmosphere loss by having fluctuations from solar wind coupling sweep ions out. Would an initial dipole magnetic field have helped? Perhaps, Maven will help elucidate all of this.

Other (or the same) evidences that I have seen mentioned are rocks that are too large to have moved without seismic activity, and that looks to have been moved within the last 100 000 years. (I should google that, but I'm short on time.)

Isn't it possible to estimate the energy that the puny core of Mars would generate as compared to Earth, and guess from there? Mars has merely 11% of the mass of Earth, is much further away from the Sun to benefit from solar radiation, and has no protective atmosphere. Could it be that it had run out of "steam" and is already as cold on the inside as it is on the outside?